1. Field of Invention
The present invention relates in general to brake systems of wheeled motor vehicles, and more particularly to the brake systems of an automatic type that automatically brakes own vehicle when a collision against a preceding object or vehicle is highly estimated.
2. Description of Related Art
Hitherto, for the purpose of safety driving, various automatic brake systems of the above-mentioned type have been proposed and put into practical use in the field of wheeled motor vehicles.
Some of the automatic brake systems are of a type that includes a radar device mounted on the own vehicle for detecting a vehicle interval distance between the own vehicle and the preceding vehicle and automatically brakes the own vehicle when a collision against the preceding vehicle is highly estimated with respect to the detected vehicle interval distance and speeds of the two vehicles.
Laid-open Japanese Patent Application (Tokkaihei) 6-298022 shows an automatic brake system of the above-mentioned type. In the system of this publication, a first safety distance capable of avoiding a collision by a brake pedal operation and a second safety distance capable of avoiding the collision by a steering wheel operation are both calculated. When a detected vehicle interval distance is smaller than either of the first and second safety distances, automatic braking takes place.
Furthermore, Laid-open Japanese Patent Application (Tokkaihei) 7-69188 shows an automatic brake system that, upon sensing the highly estimated vehicle collision, applies a slight pre-braking to the vehicle before applying a main braking for forewarning the driver of the main braking.
However, due to inherent constructions, even the automatic brake systems of these publications have failed to provide the users with a satisfied performance.